Stop collar for tube expander

ABSTRACT

A tube expander having a stop collar for limiting advance of a received tube end to a predetermined axial location relative to the expander rollers and their supporting cage. The collar is comprised of a plurality of individual L-shaped wire fingers circumferentially displaced about the cage. Each finger is spring biased radially inward against the cage periphery transversely to the path of tube advance. By this arrangement, the fingers are maintained in surface tracking relation against the rotating cage for collectively acting as a barrier against further advance by the tube end.

United States Patent 1 1 1 1 B 3,924,433

Martin Dec. 9, 1975 [54] STOP COLLAR FOR TUBE EXPANDER FOREIGN PATENTS 0R APPLICATIONS lnventofi Pal}! Warren Marti", Springfield, 511,113 10/1930 Germany 72/122 OhlO 536,136 5/1941 United Kingdom 72/122 [73] Assignee: Dresser Industries, Inc., Dallas, Tex.

Primary Examiner-C. W. Lanham [22] Flled: July 1973 Assistant ExaminerE. M. Combs [21] AppL NOJ 377,683 Attorney, Agent, or Firm-Roy L. Van Winkle; John N. Hazelwood [44] Published under the Trial Voluntary Protest Pro ram on January 28, 1975 as document no. B 357,683. [57] ABSTRACT A tube expander having a stop collar for limiting advance of a received tube end to a predetermined axial 72/393 location relative to the expander rollers and their sup- [51] Int. Cl. B21D 3/04; B211) 41/02 porting cage. The collar is comprised of a plurality of [58] Field of Search 72/ 1 individual L-shaped wire fingers circumferentially dis- 72/393, 367, 370 placed about the cage. Each finger is spring biased radially inward against the cage periphery transversely [56] References Cited to the path of tube advance. By this arrangement, the UNITED TES PATENTS fingers are maintained in surface tracking relation H 72 125 against the rotating cage for collectively acting as a 33%;: :8/123: 72/122 barrier against further advance y the tube 2,649,889 8/1953 Dudley 72/125 3,426,565 2/1969 Schott 72/125 8 Clams 3 Drawmg Flgures 35 10 12% f- 37 1/ 22 I I6\ 23 5 h m a r f a 24 1 l4 37 43 .1 i--- jig US. Patent Dec. 9 1975 3,924,433

STOP COLLAR FOR TUBE EXPANDER BACKGROUND OF THE INVENTION 2. Tube expanders are widely used by manufacturers of heat exchangers or the like for joining tube ends to headers and areavailable from a variety of commercial sources. In their usual construction, the roller and mandrel type tube expander is comprised of a tubular cage with three slots in its periphery containing rollers lying at an oblique angle to the cage axis. A rotatable tapered mandrel extends axially through the cage in driving contact with the rollers for rotating the rollers while forcing them operably outward against a tube wall thereat. With the expander initially positioned internally of a tube in engagement against the tube wall, subsequent rotation of the mandrel induces a self-feeding inward movement thereof.

By virtue of the self-feeding aspect that draws the mandrel inwardly, there is a concomitant tendency for the rotating cage to draw the tube outwardly and away from the header sheet. Because of the foregoing it is possible for the tubing to incur an axial advance beyond that which can be tolerated by the expander without interfering with expander operation. Adverse effects of the latter include improper location of the tube and/or severe damage to the expander unit per se. For avoiding those effects, it is common to employ a stop collar of sorts as, for example, disclosed in US. Pat. No. 3,426,565. To be effective, a stop collar of the specific construction disclosed in the patent must be located behind the rollers to avoid any gaps through which the tube could penetrate. If located about the rollers, a gap would necessarily be imposed from the clearance provided to avoid roller interference.

SUMMARY OF THE INVENTION The invention relates to tube expanders and more particularly to a novel stop collar for arresting axial advance of a tube end over the expander cage. This is achieved with a highly effective yet relatively inexpensive construction comprised of a plurality of individual L-shaped fingers radially extending into biased engagement against the cage periphery transversely to the path of tube advance. The fingers are of spring wire and are secured in a stationary position angularly displaced about the cage each terminating radially inward thereagainst. By virtue of their resilient quality, the fingers are able to follow the cage and rollers in a surface tracking relation during the course of their rotation. Once the advancing tube end encounters the fingers, the lateral interference provided thereby precludes any further advancement of the tube. This eliminates the necessity of being located behind the rollers in the manner of the prior art.

It is therefore an object of the invention to provide a novel stop collar for a tube expander whereby to controllably limit tube end advancement thereon.

It is a further object of the invention to provide a novel stop collar for a roller and mandrel-type tube expander capable of closely following the rotating cage periphery in surface tracking relation in order to restrict inward movement of the tube end.

It is a further object of the invention to provide a novel stop collar as in the previous objects that is highly effective yet relatively inexpensive to manufacture for arresting tube movement on tube expanders of the roller and mandrel type.

It is a still further object of the invention to provide a tube expander having a stop collar as in the aforementioned objects.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a tube expander incorporating a stop collar in accordance herewith;

FIG. 2 is a fragmentary view similar to that of FIG. 1 and partially sectioned; and

FIG. 3 is a sectional elevation as viewed substantially along the lines 33 of FIG. 2

Referring now to the drawings, there is shown a tube expander, generally designated 10, positioned internally of a tube 11 to be expanded for secured attachment to a tube sheet or header 12.

Comprising the tube expander is a tapered mandrel 14 adapted to be rotatably driven at its end 15. Positioned about the mandrel to I be rotatably driven thereby is a cylindrical cage 16 containing three cylindrical forming rollers 17. The forming rollers are circumferentially displaced in the cage periphery obliquely skewed to its axis and supported on the mandrel to be rotatably driven thereby. Rearwardly of the rollers and likewise positioned about the cage is a thrust collar 18 enclosing a thrust bearing 19. Behind the bearing is a thrust nut 22 positioned on cage threads 23 andvcoupled to cage 16 via a set screw 24. An annular retainer spring 25 extending into an inward collar recess 26 maintains the components in their assembled relation whereby collar 18 will remain stationary relative to cage 16 which is free to rotate.

Forming thrust collar 18 is a front tubular section 30 closely surrounding cage 16 of internal diameter 32 affording a clearance 33 at least sufficient to clear the circle of maximum expansion afiorded by rollers 17. integrally joined with front section 30 is an enlarged rearward tubular section 31 in which bearing 19 is contained. To preclude or restrict tubing 11, even when of thin wall construction, from being drawn inwardly of the annular clearance between the thrust collar and cage there is provided a stop collar 35 constructed in accordance herewith.

Comprising stop collar 35 is a plurality of fingers 36. Each of the fingers is of spring wire or the like of about A; inch diameter formed L-shaped to afford an axially elongated arm portion 37 and a radially extending leg portion 38. The fingers are circumferentially displaced uniformly about the thrust collar 18 with the terminal end of each arm 37 received in a collar aperture 42 whereat the finger is secured by means of a set screw 43. From beneath a set screw 43, each finger arm extends generally in an axial direction toward rollers 17 until laterally offset by leg 38. The leg then passes radially through aperture cutouts 47 flush with the front face of collar 18 until leg end 48 terminates in engagement against the periphery of cage 16 and/or rollers 17.

The dimension of radial leg 38 is sufficient for end 48 to engage the periphery of cage 16 while causing arm portion 37 to stand outwardly bowed from the periphery of collar tube 30. Being bowed in this manner the finger is maintained in a spring tension biased at all times inwardly against the cage. Since each finger is individually biased independently of the other each will track the alternating surfaces of rollers and cage moving therepast in their course of rotation. In that manner, the constant engagement between fingers and the rotating periphery collectively precludes any penetration of tube 11 axially beyond engagement with the fingers, even with a tube of thin wall construction.

By the above description, there is disclosed a novel stop collar construction for a tube expander. The collar 35 is comprised of a plurality of resilient fingers 36 that accurately end track surface rotation of the cage 16 and forming rollers 17. Should tube 11 be of thin wall construction otherwise capable of penetrating clearance 33, the fingers axially located flush with the face of tube 30 collectively effect a lateral barrier against such penetration to inwardly of the thrust collar. By this means, effectiveness of the stop collar is highly reliable yet by virtue of its simplicity is relatively uncostly to manufacture affording it decided advantage over competitive expanders having similar purpose stop collar devices.

Since many changes could be made in the above construction and many apparantly widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specifications shall be interpreted as illustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a tube expander including a rotatable tubular cage about which to receive a tube end to be expanded, forming rollers contained in the outer periphery of said cage and a rotatable tapered mandrel within said cage for driving said cage and rollers in an expanding relation to a tube and received thereon, a substantially nonrotatable stop collar adapted for limiting axial advance of a received tube end onto said cage, said stop collar comprising a plurality of individual means disposed circumferentially about-said cage operably independent of each other, said individual means each extending into engagement with the periphery of said cage at a predetermined location in the path of tube advance, and being operably adapted to follow the rotating periphery of said cage and rollers in a surface tracking relation therewith.

2. In a tube expander according to claim 1 in which said individual means extend radially toward said cage to impose a lateral barrier in interfering relation with the end of a received tube for limiting axial advance thereof.

3. In a tube expander according to claim 2 in which said individual means are comprised of a resilient material fixedly supported and radially biased into said surface tracking relation.

4. In a tube expander according to claim 3 in which said individual means comprise individual L-shaped fingers each having one end that terminates in said surface tracking relation.

5. In a tube expander according to claim 4 in which said fingers are of a spring wire composition.

6. In a tube expander according to claim 5 including a thrust collar having a plurality of apertures in which to receive and support said fingers and means to secure a finger in each of said apertures.

7. In a tube expander according to claim 6 in which each of said fingers is comprised of an arm portion generally extending in an axial direction from one of said apertures and a leg portion generally extending in a lateral direction from said arm portion radially toward the periphery of said cage.

8. In a tube expander according to claim 7 in which the radial extent of said leg portion is generally greater than the radial distance of said cage periphery to the finger supporting aperture in said thrust collar. 

1. In a tube expander including a rotatable tubular cage about which to receive a tube end to be expanded, forming rollers contained in the outer periphery of said cage and a rotatable tapered mandrel within said cage for driving said cage and rollers in an expanding relation to a tube and received thereon, a substantially non-rotatable stop collar adapted for limiting axial advance of a received tube end onto said cage, said stop collar comprising a plurality of individual means disposed circumferentially about said cage operably independent of each other, said individual means each extending into engagement with the periphery of said cage at a predetermined location in the path of tube advance, and being operably adapted to follow the rotating periphery of said cage and rollers in a surface tracking relation therewith.
 2. In a tube expander according to claim 1 in which said individual means extend radially toward said cage to impose a lateral barrier in interfering relation with the end of a received tube for limiting axial advance thereof.
 3. In a tube expander according to claim 2 in which said individual means are comprised of a resilient material fixedly supported and radially biased into said surface tracking relation.
 4. In a tube expander according to claim 3 in which said individual means comprise individual L-shaped fingers each having one end that terminates in said surface tracking relation.
 5. In a tube expander according to claim 4 in which said fingers are of a spring wire composition.
 6. In a tube expander according to claim 5 including a thrust collar having a plurality of apertures in which to receive and support said fingers and means to secure a finger in each of said apertures.
 7. In a tube expander according to claim 6 in which each of said fingers is comprised of an arm portion generally extending in an axial direction from one of said apertures and a leg portion generally extending in a lateral direction from said arm portion radially toward the periphery of said cage.
 8. In a tube expander according to claim 7 in which the radial extent of said leg portion is generally greater than the radial distance of said cage periphery to the finger supporting aperture in said thrust collar. 